Direct climate intervention strategies on Earth (geoengineering, or more colloquially “terraforming”) have not generally been viewed as a benefit, but more as a hazard. In light of current trends in climatology, it may be necessary to rethink these reservations. For starters, unintended geoengineering is well underway on a massive scale, and there is convincing evidence of anthropogenic causality for climate change. Current anthropogenic release of carbon dioxide from fossil fuels and cement production is about 7 GtC/yr (7 metric gigatons as carbon) annually and may reach 12 GtC/yr by 2050, with probable net doubling of atmospheric CO2 in the lifetime of our children. This inadvertent geoengineering was inevitable given the greenhouse forcing we have caused by fossil fuel combustion, and the only subject of debate (FIG. 1) is the intensity of its future impact. Among the complications we are seeing today: overpopulation, violence, economic collapse, poverty, deforestation and desertification.
The scale of the problem is difficult to grasp. Future atmospheric CO2 concentrations in the year 2100 are projected by the IPCC to be in the range of 540 to 970 ppm, compared to only 370 ppm in the year 2000, 400 ppm in the year 2013, and less than 280 ppm before the industrial revolution. Perhaps more impressive than concentration are the pool sizes themselves. Current atmospheric total CO2 is about 750 GtCO2 as mass, a doubling of the 360 GtCO2 in the atmosphere less than 200 years ago.
Also of interest are the current flux rates. Fossil fuel export to the atmosphere is more than 6 GtC per year at present and is increasing sharply. Of this, about net 2 GtC is being absorbed in the oceans annually (about 30% of the carbon dioxide emissions from fossil fuel combustion). Since 1800, the ocean has absorbed about 135 GtC carbon dioxide; and has become correspondingly more acidic. Interestingly, higher rates of increase in atmospheric CO2 tend to occur in El Niño years, as would be consistent with a Henry's Constant effect on the atmospheric/marine solubilized carbonate species equilibrium. Currently, the pool size of inorganic carbon in the mesopelagic water column is about 5.4 GtC, ensuring that atmospheric CO2 will continue to rise for centuries, even if fossil fuel combustion is stopped tomorrow.
In addition, there is a high risk of positive feedback, the so-called “runaway” greenhouse effect. Total CO2 pools incipiently releasable into the atmosphere (from long term sequestered stores in permafrost and methane hydrate deposits) as carbon are measurable in Teratons (i.e. exceeding 1012 tons as carbon). Because these pools are orders of magnitude larger than the existing total atmospheric pool, it should be clear that activities that could cause their release into the atmosphere are likely to result in mass extinctions at all levels of the food chain. The trigger for melting permafrost and release of methane hydrate pools held in place by the ice caps may have already been pulled, but in light of the magnitude of the potential CO2 release, it seems eminently sensible to act quickly to attempt to quickly reverse our present course.
Yes, we are responsible for these transformations. Total human energy use is measurable in exaJoules (and is about 1000 EJ or 1021 J annually). Of that, about 40% (400 EJ) is currently derived from fossil fuel consumption. Conceptually, a burning candle can be imagined as equivalent to 0.8 J/s, so that the rate of human energy consumption is equivalent to perhaps 50 trillion candles burning simultaneously, or 6,000 candles for every person on the planet, all burning around the clock. More conventionally, the number is about 10-20 MWhr/capita in developed countries, or potentially 1-2×1010 MWhr for the global population, assuming a peak population of 9 or 10 billion and a “Western” standard of living. Notwithstanding the population overshoot, clearly the practice of burning anything to meet this kind of energy load is unsustainable, and perhaps the standard of living itself is unsustainable given the population base. Geoengineering is not a small thing to have done by accident, and it will not be a small thing to undo.
Therefore, there is an urgent need to re-engineer the planetary economy, both by restructuring industry, feedstocks, carbon footprints, and the like, but also by ameliorating ongoing damage to our shared “commons”, the atmosphere and the oceans. This constitutes remedial terraforming, but here is termed “rational geoengineering” to better differentiate the science from the science fiction.
Rational approaches to geoengineering can be divided into two categories: biological and physical. Among the biological approaches are: carbon sequestration by marine fertilization and terrestrial or marine silviculture. Among the physical approaches are: injection of microparticulate reflectors into the stratosphere (as per the “Pinatubo Effect”); extraterrestrial solar parasols; carbon dioxide storage in geological formations (generally as carbonates); carbon dioxide storage in deep sea lakes (as liquified CO2), and the like. The scale of any such project can be judged by comparison with more conventional alternatives: for example, an immediate roll-out of 6,700 new nuclear power plants (assuming 6.8 GWhr per plant, sufficient enriched uranium, and no waste in electrical distribution) would be required to zero out power consumption derived from fossil fuel alone (fossil fuel consumption is currently about 400 EJ or 4.6×107 GWHr annually and rising). At current cost of US$ 10B/plant, construction of an adequate number of nuclear power plants would amount to US$ 65 Trillion in present dollars and would take decades. Currently, less than 500 nuclear power plants are installed worldwide.
There are alternatives. Solar power is dependent on solar insolation, an essentially free energy source which averages out to about 160 W/m2 (160 J/s/m2) over the surface of the planet. Again taking 400 EJ as the target, replacing today's fossil fuel combustion with photovoltaic cells operating at 10% efficiency would require a solar panel array (or combined equivalent) the size of Venezuela, more than 400,000 km2 if placed equatorially. Also a factor is the heat required for manufacture, such as by the Czochralski process, and periodic replacement of solar panels, capacity for which is practically nonexistent considering the scale. Current solar cell designs radiate heat as black bodies, emitting a great deal of waste heat, so that on the scale envisaged, heat emission from the required surface area of solar cells is likely to reach 2000 EJ annually (assuming 50% conversion to “new” heat), five times the current heat generated from fossil fuel combustion! Like water, conventional solar cells have the albedo of black asphalt. Taking solar insolation at the terrestrial surface as about 45 PW, the incidental heat pollution of the solar panels would be 4% of the overall global surface heat budget. Net flux of heat IN will exceed net heat OUT until a new global surface temperature at equilibrium is reached. The effect would be analogous to removing the high-albedo icesheet from Greenland and replacing it with a low-albedo asphalt surface, but positioned equatorially.
Measurements in support of a dramatic climate forcing by terrestrial albedo are readily found. In a widely cited paper by Palle (2004, Science 304:1299-1301), an observed decrease in global albedo of 0.02 was associated with an increased global heat budget of 6.8 W/m2, a highly significant increase climatologically. Much of the decrease in global albedo is the result of anthropogenic changes in land use, vegetation, burning of forests, and deposition of soot upon snow. Installation of solar panels has been added to that list.
Currently, installed wind power on line is about 157 Million MWHr or 0.34% of global demand. The Picken's plan in Texas would add 4,000 MWHr to this total, a rather small amount expected to cost $10 billion. Within a few decades, because of the constancy of wind in Patagonia, more than 1.3 Trillion MWHr per year could be installed, or about 3.2% of global demand. But these areas of sustained strong wind are unusual and the estimates do not factor power losses through an electrical distribution grid or losses in a conversion process to liquid fuel for export.
Arable land required for biomass energy capture and conversion is estimated at anywhere from 13,700 to 32,000 km2/EJ. To capture the equivalent of 400 EJ, perhaps 8×106 km2 must be converted to cropland, an area the size of Australia, or about 5% of the earth's land mass. This does not factor in the overhead energy costs of farming, which should perhaps double the area needed. Currently, about 1.3×106 km2 is under cultivation in the US for food crops. So again, the undertaking is beyond enormous—energy crops cannot simply replace food crops worldwide without major sociopolitical consequences. The irreplaceable and unsustainable bounty of readily available fossil fuels simply cannot be overstated.
Population extinction by economic pressure has also been considered as a solution to the climate dilemma we face, but the social dislocations of such a program pose considerable risks to those who would execute it, no matter what walls are constructed. In an article titled, “Guns beat Green”, writer Naomi Kline, writing in the December 2007 The Nation, shows that market investments favoring a fortress mentality, private security for the wealthy and weapons at the borders, surpassed new investments in sustainable energy technologies. Weapons and security technologies received 6 Billion $US in venture capital in 2007 whereas green technologies received only 4.3 Billion, and the gap has been widening. Peak oil is on the near horizon, consumers are increasingly turning to natural gas, and the consensus in the stock market seems to be that those with the guns will consume the last gallon of gasoline, the last cubic foot of natural gas, and the last bucket of coal! Clearly the betting money is on economic Darwinism to solve the problem of climate change. But can we truly sustain a Maginot Line or Demilitarized Zone in the face of new and greater waves of hungry illegal immigrants at our borders? Can we fortify our communities and not be impacted by a worldwide collapse of democratic values, commodities, currencies, and access to markets such as we are now seeing?
Clearly, no single program is feasible at the scale required. Conservation efforts, for example business metrics based on “carbon footprint”, are laudible but not yet up to the Draconian task required to eliminate 400 EJ from the annual global energy budget. Although comforting, and in the short term profitable to some, recent innovations in carbon trading are far from meaningful net reductions, and are in fact a sort of shell game that in all likelihood attempts to obfuscate the scope of the problem in the name of corporate public relations.
Alternatives to the handling of fossil fuels have also been proposed. What is euphemistically termed “clean coal” technology, for example, proposes to inject by-product CO2 from coal gasification or power production into sub-terrestrial strata such as depleted oil fields. While this sounds attractive, the changes in albedo and atmospheric CO2 resulting from use of coal are more likely than not to result in a net planetary heat gain and is unsustainable.
Finally, business as usual is clearly not an option, such a course posing unacceptable hazards and burdens for future generations. Part of the problem relates to the reluctance of human societies to put a value on the commons, for example a tax or “debit” for use of the atmosphere as a “sink” for CO2 (and heat) generated by an industrial process. Heat can also be considered a waste, and while it may be convenient for the polluter to dump it into the atmosphere or an ocean, there may be a social cost or lost benefit not currently taken into account in our economic balance sheets. Exacting payment for heat disposal would be difficult however, excepting contracting to a Maxwell's Demon, unless there was a way to actively transport net heat from the planet and “credits” for that ameliorative process could be issued and traded. As discussed here, such a system is not impossible, but requires engineering deliberate increases in terrestrial albedo, and in the short term, reductions in atmospheric CO2.
Can/will the greenhouse effect be slowed down? FIG. 1 suggests the current trend in global mean temperature, which is tied closely to CO2 release into the atmosphere. Note that 2100 does not bring a plateau in the relentless rise in global mean temperature that started in the late 20th century, and we are again forced to ask whether our lifestyle presages retreat of temperate climate zones poleward, deforestation by fire and insect population explosions, and mass extinctions.
In addition to combustion of fossil fuels, other sources of greenhouse gases must be considered. Pre-industrially, deforestation accounted for about 75% of the total annual increase in atmospheric carbon dioxide, but is now only about 20%, having been swamped by rising fossil fuel combustion. Globally, the four activities responsible for most CO2 emissions are: 1) fossil fuel combustion, 2) deforestation, 3) agriculture and 4) manufacture of Portland cement.
Conversion of native ecosystems to cropland or pasture continues to be associated with both soil deterioration and release from soil humus of up to perhaps 1.5 Tt of sequestered carbon, an ongoing process. Remaining fossil fuel reserves, importantly including coal, are estimated at over 5 Tt C (18 Tt CO2), and most of this is being developed or evaluated for “exploitation”, perhaps understandably given the market premium placed on the value of gasoline, which is only likely to rise. Not surprisingly then, use of fossil fuel reserves seems to be accelerating. Psychology is a critical factor confounding the hard science of global warming, and there will be a need for temporary relief, a cooling off period, so that the reality of the situation can be fully assimilated and a sober commitment to a sustainable future can be engendered.
There had been an expectation for some time that a negative feedback mechanism in global climate would emerge, a sort of “Gaia-effect”, perhaps in the form of increased oceanic albedo through cloud condensation nucleii as proposed by Robert Charlson of the University of Washington in 1987 (Nature 326:655-61). However, we can also expect the opposite—positive feedback effects. One such example is found in the expected effects of a meltdown of the West Antarctic ice sheet. Accounting for the rebound of the Earth's crust following relief from the weight of the ice sheet, and resulting shift in polar axis of rotation, the predicted 5 m sea level rise is expected to be even higher, perhaps 6.3 m, in the northern hemisphere, where the bulk of the continents are located (Mitrovica, J X et al. 2009. The sea level fingerprint of West Antarctic collapse. Science 323:753). Increased ocean surface area resulting from continental flooding can be expected to dramatically reduce global albedo over large areas, in aggregate reducing reflected heat and increasing the temperature “set point” of the planet. A similar positive-feedback potential of carbon release from permafrost and methane hydrates (pool size >1 TtC) has already been mentioned. No deux-ex-machina to cool the planet can be relied on; it appears we are on our own.
Divine intervention aside, an exponential reverse J-curve in economic activity and population is the more likely negative feedback we can expect in the short term. Deceases in human activity have been associated with periods of relief. For example, changes in agriculture and silviculture practice across northern Asia following the dissolution of the Soviet Union resulted in measurable decreases in radiative forcing due to greenhouse gas heating (i.e., decreases in livestock husbandry resulting in decreased production of methane) and increases in forest carbon dioxide sinks (by decreases in timber harvesting). Ruddiman has proposed a related argument associating cooling trends observed following first contact of Europeans and Native Americans. Similarly, slowing of global economic activity due to the 2008-2013 banking crisis will likely be shown to have reduced carbon dioxide output. At the very least, a decrease in carbon dioxide output and global warming superimposed on a downturn in human economic activity will relieve any lingering doubts in the minds of planners that greenhouse warming is anthropogenic at its belly button.
Thus by the process of elimination of alternatives recited here, geoengineering must be seriously considered as part of any comprehensive effort to solve the problem—absent any compelling argument to the contrary. Two arguments against rational geoengineering are commonly made. First that the ecological risks are unacceptable. Second that any ameliorative action taken would ease the pressure to make the hard decisions needed to develop a sustainable energy economy. Both these arguments will likely wilt when and if global warming enters a “runaway” phase. Arguments about ecological risk must seem hypocritical even now given the reckless behaviors that have produced the crisis. In short, it seems inevitable that resistance to rational terraforming will evaporate when temperatures or sea level spikes sharply. Therefore the “roll-out” of any terraforming device must have a short lead time and quickly become effective. It is reasonable to want to prepare for this while organized economic activity on a global scale is still possible. Preliminary studies undertaken at this time, undertaken to ensure that an effective response will be available when the political urgency becomes compelling, seem entirely defensible and in fact of the highest priority.
A worst case acute meltdown and global temperature spike would likely be marked by a sharp upturn in fossil fuel combustion emissions and then a generational declining standard of living: simply because the costs of adapting to planetary ecosystem disruption will be so high. More optimistically, the crisis could spike and then correct itself through adoption of new technologies over several decades, peaking sometime between 2020 and 2050—maybe. Optimally, a geoengineering device and method for amelioration of the global heat budget and greenhouse effect might be required for a few years or a decade to blunt peak emissions, following which we ultimately make more sustainable choices for powering a quality of life for all. Thus a geoengineering apparatus or process would thus simply be a means for gaining the time needed for committed change, and conveniently, would then dissipate and vanish without further intervention, or could be turned off or redirected. In this view, rational geoengineering is seen not as an artifice to evade, but rather as a potential borrowing of time to face an incipient crisis and make the necessary changes.
One geoengineering proposal has emerged as feasible, economical, and likely to be effective, albeit with uncertain collateral consequences. In the Pinatubo eruption, approximately 10 Mt sulfur as a SO2-rich aerosol was transported to stratospheric levels above 30 km. The plume, covering a band of some 125,000 km2, reduced global insolation, when measured 6 months later, by about 4.5 W/m2 (or global mean average of about 3%). Mean global temperature dropped by about 0.5 degrees Celsius (0.9° F.) for over a year following the eruption. A similar impact was seen after the El Chichon eruption of 1982 and after Tambora, another stratovolcano, in 1816, which was followed by a “year without a summer” and crop failures in Europe. Nobel Prize winner Paul Crutzen has published a thumbnail feasibility study for NASA-assisted injection of nanoparticles into the stratosphere, offering to mimic the beneficial cooling effect that follows stratovolcanos. (see www.deas.harvard.edu/climate/pdf/2006/Crutzen2006.pdf). In short, a significant increase in planetary albedo can be achieved by any party possessing the capacity to lift 100 Mt of volcanic ash into the stratosphere, purportedly a relatively cheap proposition. The “Pinatubo Effect” as it is now called, was equivalent to 0.75 W/m2 in reduced insolation. However, sulfur dioxide attacks ozone and precipitates as acid rain. A better choice of aerosol might be microparticulate olivine, mica, or diatomaceous earth, which are available in abundance. But doubts as to the feasibility and safety persist.
Some work toward marine geoengineering was initiated on a small scale as early as 1993, and the results have been confirmed in numerous subsequent studies. As set forth in detail at www.palomar.edu/oceanography/iron.htm (accessed 30 Jan. 2007), the IronEx I research vessel Columbus Iselin set out to sea in 1993 fitted with a portable laboratory and loaded with 21 barrels of blue-green iron granules (about 0.5 t of ferric sulfate). The mineral was dissolved in seawater at the test site and dispersed in a location SW of the Galopagos Islands. Application resulted in increase of iron from about 20-50 pM to about 1-2 nM and a three-fold increase in phytoplankton (measured as chlorophyll) in the treated area. The biological enrichment resulted in transient sequestration of about 300 t carbon dioxide over a two week period but was complicated by unexpected surface stratification. This experiment generated a tremendous debate and was repeated in 1995, with yet better results, stimulating a 30× increase in surface chlorophyll, principally in the form of diatoms, but also higher trophic levels, as had been predicted. An estimated 9,100 t of carbon dioxide was drawn down. Encouragingly, follow up work has not demonstrated significant collateral production of NOX or methane.
The effort was originated in 1986 by John Martin of Moss Landing Marine Laboratories, and was first disclosed in response to a presentation by Bruce Frost of the University of Washington, who had noted that some ocean areas were unexpectedly phytoplankton poor (the “high-nitrate/low chlorophyll” oceans), for example the Pacific equatorial belt extending east from Irian Jaya to Peru and the roaring 40's, the belt of water surrounding Antarctica. Martin had suggested that biological productivity was limited by iron availability, and that iron fertilization would result in a phytoplankton bloom and could be used as a means to reduce the greenhouse effect (which was already well understood in scientific circles by the 1980's) by sequestering carbon dioxide. See for example, Martin et al. 1990. Glacial-interglacial CO2 change: The iron hypothesis. Paleoceanography 5:1-13 and discussions [www.palomar.edu/oceanography/iron.htm] of the period. Use of marine fertilization with iron to stimulate marine productivity and sequester CO2 is thus not a novel concept and a first full, clear and definite conception was articulated in the mid-1980s.
In the second Iron-Ex expedition, in 1996, headed by Kenneth Coale, it was noted that the redox state of the inorganic iron was important, ferric iron precipitating rapidly as the hydroxide and exiting the photic zone. Nonetheless, a dense and somewhat anoxic phytoplankton bloom was observed and documented.
Other experiments of this same kind have since been published (see Tsuda A et al. 2003. A mesoscale iron enrichment in the western subarctic Pacific induces a large centric diatom bloom. Science 3009:58-61; Markels and Barber. 2001. Sequestration of CO2 by ocean fertilization. Poster Presentation for NETL Conference on Carbon Sequestration; Boyd P W et al. 2000. A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization. Nature. 407:695-702; Coale K H et al. 2004. Southern Ocean iron enrichment experiment: carbon cycling in high- and low-Si waters. Science 304:408-14; Boyd P W et al. 2004. The decline and fate of an iron-induced subarctic phytoplankton bloom. Nature 428:549-53). A total of 12 experiments were recently reviewed by Boyd (Boyd P W et al. 2007. Mesoscale iron enrichment experiments 1993-2005: synthesis and future directions. Science 315:612-7). A newsworthy update was recently published in Science (318:1368-70, 2008).
Patent literature has also accumulated, beginning with a 28 Apr. 1994 filing by Markels (U.S. Pat. No. 5,433,173), which claimed a method for first measuring nutrients in seawater, of then adding any missing nutrients to the seawater, and finally harvesting the increased production as seafood. Use of a “float material” such as rice hulls, wheat chaff, ground corn cobs [and] peanut hulls was proposed as a form of fertilizer that would dissolve in the surface over a period of days, or perhaps as long as a week. The detailed description involved shipboard pumping of a liquid fertilizer composed primarily of iron with some phosphates and nitrates, and disclosed “that almost certainly algae will grow”. It can be said that John Martin unequivocably articulated that same assertion almost a decade earlier. Markels' patent was awarded with narrow claims.
This was followed by U.S. Pat. No. 5,535,701, which cited one of the Martin papers (Martin et al. 1994. Testing the iron hypothesis in ecosystems of the equatorial Pacific Ocean. Nature 371:123-129). In the second filing, the method was supplemented by further providing a nitrogen-fixing organism with the fertilizer. As examples of compositions for such use of fertilizers, starch mixtures with iron were suggested. Compositions were again not claimed.
In U.S. Pat. No. 5,967,087, Markels claimed a method for increasing seafood production, where the fertilizer contains iron in a chelated form so that the iron does not precipitate from the photic zone as hydroxides. Compositions for the method were disclosed. The compositions included binders such as plastic, wax, or starch to provide timed release over two weeks of the fertilizer, and a plastic pellet matrix compounded to float by attaching the fertilizing matrix to a float material such as glass bubbles, plastic foam, or by introducing gas bubbles into the fertilizer pellets during manufacture. The matrix selected for attaching the fertilizing elements to the float element or for introducing gas bubbles into the fertilizer pellets was taught to be a plastic matrix, or optionally a wax (Col 4 lines 48-65). Again the timed release matrix disclosed was selected to dissolve in two weeks or less, and in subsequent disclosures, pulse fertilization at intervals greater than 30 days was reported as preferable.
In 2000 and 2002, two US patents issued to Markels claiming methods for sequestering carbon dioxide by ocean fertilization. In U.S. Pat. No. 6,056,919 the steps of the claimed method involve testing to identify a missing nutrient, applying a fertilizer to supply the nutrient, limiting the bloom by applying the fertilizer in pulses, and measuring the amount of carbon dioxide sequestered. Pulse application at intervals of greater than 30 days (see independent claims 1 and 15) was taught to limit anoxia in the phytoplankton blooms. It is known that micrograzing and eutrophication result in lessened carbon sequestration.
In U.S. Pat. No. 6,440,367, methods of applying iron chelates to the ocean were claimed for sequestration of carbon dioxide. Disclosed was an iron:lignin chelate. In this case, and all such related cases, the teachings teach away from the use of the less expensive insoluble mineral forms, which would be expected to precipitate if mixed into the ocean—an unsolved problem.
US Patent Appl. 2002/0023593 relates again to methods of increasing seafood production. Claims 1, 10 and 14 summarize the relevant teachings as to compositions: [a method wherein] first, iron is to be supplied as a chelate, and secondly, “said second fertilizer is in the form of pellets, and said pellets comprise a float material selected from gas bubbles and/or low density materials, and said pellets further comprise a binder selected from plastic, wax, high molecular weight starch, or a combination thereof”. Any such composition consists of an organic binder, a float material, and an iron chelate, but note that the claims relate strictly to methods, and that in all the claims in this series, the steps are always to measure the nutrient concentrations in seawater, to determine the limiting nutrient, and then to supply that nutrient, the substance of what John Martin had proposed for iron-poor oceans. A method in which the limiting nutrient is not measured is not claimed, although most scientists would be reluctant not to collect baseline data before undertaking iron enrichment as a matter of ordinary skill in the art. Also not conceived was a method in which non-limiting nutrients were added, for example so as to favor certain communities over others.
As for compositions, the methods of the prior art teach solubilized minerals, chelates, and a narrow genus of pellet matrices selected from the list of organic chemicals consisting of plastic, wax, and starch. All such pellets contain an organic binder. However, selection of an organic matrix is problematic in that the named materials are responsible for very high levels of biological oxygen demand, starch for example, thus promoting the growth of heterotrophs, particularly bacteria not native to the pelagic ocean, which will certainly exacerbate oxygen depletion in the underlying water and reduce carbon sequestration by resolubilizing any carbon dioxide fixed by primary producers. Plastic materials are also a major pollutant in the world's oceans and typically contain carcinogenic plasticizers. Wax is not expected to form monodisperse sustained-release pellets absent a surfactant and is difficult to handle. Other objections to the selections taught by Markels could be elaborated here. Organic binders will likely have a highly negative effect on ocean surface chemistry by disintegrating into short chain oils and organic polymers, and thus displacing native surfactants, chelators, siderophores, and the like from the neuston, which is a critical environment in pelagic ocean biology.
Similar problems are found with organic materials as a genus, such as the rice crispies and peanut hulls proposed as float materials. While the use of “glass bubbles” as a float material is attractive, current supplies of hollow glass microspheres, as the term “bubble” would be understood by one skilled in the arts, are expensive and the Markels disclosures teach an organic binder or matrix selected from plastic, wax and starch wherein the glass bubbles are added to the matrix solely for buoyancy.
The work to date has also been criticized by others because supplementation with the limiting nutrient in one area will necessarily deplete the water body of other nutrients, which then become limiting as the water body moves out of the test area. In other words, while some hope to profit by fertilizing within a fence, the profit is robbed from areas outside the fence, a classical retelling of the tragedy of the commons. As an example, see U.S. Pat. No. 6,729,063, where the problem is made transparent. The method of first measuring limiting nutrient concentrations in a body of water and then supplementing that body of water with an excess of the most needed nutrient or nutrients is thus fundamentally flawed, and increases productivity in the test site by robbing the productivity of adjoining areas. To the extent that this is also the Martin Iron Hypothesis, the hypothesis has been highly instructive and successful, but is flawed as a method for rational geoengineering.
In short, the prior art has taught inter alia that higher bioavailability of the nutrient supplement is preferable, that formation of insoluble hydroxides of metals is unfavorable and is prevented by chelation, and that pulse administration is necessary to prevent eutrophic blooms. But what if there was a better way?
There remains a need for a composition of a marine fertilizer formulated to overcome the above disadvantages and to provide for sustained release of a balanced palette of micronutrients over a growing season or more. Such a composition may be of benefit in increasing harvestable species while also sequestering atmospheric carbon dioxide. Valuable characteristics of such a composition include provision of increased surface area for habitat, providing spatial richness of niches as well as a nutritive leachate (noting that surface chemistry and biochemistry is sufficient, i.e. not requiring exogenous chelators, to ensure that bioactive mineral forms are released at equilibrium rates for uptake). Changes in redox species of a mineral are achieved simply by supplying a surface on which they may be bound, eliminating the need for what is meant in the chemical art by “chelators”. Because surfaces alone also result in “passive” shifts in the equilibrium concentrations of the redox species toward slow sustained release of soluble species and further supply habitat niches for microbiota that further modify the release of those mineral species as native organic complexes, accumulation of biomass is highly favored. This biomass can result in macro-sedimentation or can be harvested, or a combination of both, and is net new production. In preferred forms, these compositions are buoyant to ensure a T0.5 of greater than 3-6 months in the photic zone and are optionally reflective on a skyward surface so as to provide immediate SST cooling. Light is not limiting except seasonally at polar latitudes!
An area of particular interest involves the design of nutrient formulations to promote the growth of particular community foodchains and the associated primary producers. For CO2 sequestration, for example, it may be preferable to select a formulation that promotes the growth of coccolithophorids in preference to diatoms. Phaeocystis antarctica takes up twice as much CO2 per mole of PO4 removed than do diatoms, it has been reported. Foraminifera deposit calcium carbonate shells, a preferred sequestration and deposition mineral. Optionally, for cloud formation (termed here “kumogenesis”), it may be useful to increase dimethylsulfide production by selection of an enrichment medium that increases expression of the prymnesiophyte-microzooplankton envirotype (see Boyd P W et al. 2000. A mesoscale phytoplankton bloom in the polar southern ocean stimulated by iron fertilization. Nature 407:695-702). At some surface fill factors, gas exchange is reduced, but this can be adjusted or even overcome by physical design of the formulation. Referring again to the CLAW hypothesis formulated by Charlson, Lovelok, Andreae and Warren (Nature 326:655-661, 1987): dimethylsulfide (DMS) is thought to play a role in regulating the temperature of the planet by regulation of kumogenesis and associated cloud albedo. Dimethylsulfonio-propionate (DMSP) is biologically converted to DMS (a volatile compound), the main source of organic sulfur in the atmosphere above the oceans. Phytoplankton produce DMS that escapes into the atmosphere where it is oxidized to sulfuric acid, which acts as a nucleus for the condensation of water, and ultimately contributes to the albedo of the planet. According to the hypothesis, when cloud albedo increases, less solar radiation reaches the microbial plankton populations resulting in less photosynthesis and less DMS production, thereby creating a feedback loop that modulates the Earth's temperature [not allowing for the limiting effects of nutrients other than sulfur, which must complicate the model]. Experiments have shown that if the mixed layer depth is very shallow, then almost 100% of DMSP is converted into DMS, and as the mixed layer depth increases this value goes down. Using the mixed layer depth, chlorophyll concentrations and the DMS relationship, predicted DMS concentrations were nicely correlated with the real DMS concentrations in work by Rafel Simó and colleagues reported in Nature in 1999.
Provision of habitat in the form of bioactive surface area also has the effect of increasing trophic levels in rough proportion to the area and niche size of the habitat, a scalar porosity factor with a fractal dimension.
In contrast, current solution fertilization methods result in increases in dissolved organic carbon, picoplankton and, if sustained, bloom populations of micro-grazers such as copepods with associated anoxia and collapse of active photosynthesis. Any increases in CO2 uptake are transitory.
In the oligotropic ocean, picoplankton predominate. The fecal sediment fall is thus a “micro-sediment” with poor sedimentation characteristics that is rapidly re-solubilized as CO2 and organic acids by the action of heterotrophs. Regeneration of CO2 continues into the mesopelagic zone due to the slow descent and long residence time of the microparticles. It is well established that pelagic “microzooplankton” are the principal grazers on marine phytoplankton (Billett, D et al. 1983. Seasonal sedimentation of phytoplankton to the deep-sea benthos. Nature 302:520-522; Ryther, J H. 1969. Photosynthesis and fish production in the sea. Science 166:72-76; Falkowski, P G et al. 2000. The global carbon cycle: a test of our knowledge of the Earth as a system. Science 290:291-294; Turner, J T et al. 2000. Accumulation of red tide toxins in larger size fractions of zooplankton assemblages from Massachusetts Bay, USA. Mar Ecol Prog Ser, 203:95-107; Smayda, T J. 1970. The suspension and sinking of phytoplankton in the sea. Oceanogr Mar Biol Ann Rev 8:353-414; Irwin A J et al. 2006. Scaling-up from nutrient physiology to the size-structure of phytoplankton communities. J Plankton Res 28:459-471; Richardson, T. and Jackson, G. 2007. Small phytoplankton and carbon export from the surface ocean. Science, 315:838; Zarauz L et al. 2009. Changes in plankton size structure and composition, during the generation of a phytoplankton bloom, in the central Cantabrian sea. J Plankton Res 31:193-207). Micro-sediment sinks more slowly and is more likely to be re-solubilized. The result is that relatively little micro-sediment crosses the “100-Year Horizon” at depth as required for permanent sequestration and a significant fraction of inorganic carbon accumulates in the mesopelagic zone.
As disclosed here, this can be seen principally as an effect of habitat size, and the primary geoengineering intervention that can increase the size and quantity of sediment is not nutrient level but is instead habitat size and complexity, which effectively correlates with size of organism, number of trophic levels, and size and speed of sedimentary deadfall due to larger particle size. With provision for habitat and nutrient levels capable of supporting higher trophic levels as taught here, “macro-sediment” is obtained, and there are associated significant increases in CO2-derived organic matter descending below the 100-Year Horizon. Not only is net productivity increased, but the quality of the deep ocean fixed carbon efflux (or “biological pump”) is improved.
Ocean productivity in the form of net biological carbon assimilation is variously estimated at 36-48 GtC/yr, globally in aggregate, an impressive number. This marine productivity is about half of all global productivity, but is spread over an area of about 361×106 km2 (almost three times the area of terrestrial ecosystems). Blooms can yield 50 gm/m2/day of new fixed carbon but it is more typical to encounter oceans where productivity is on the order of 3-5 gm/m2/yr. Corridors of higher productivity tend to be localized, geographically limited, and seasonal (such as coastal upwelling or at the equator) and a method for increasing productivity in less productive areas of the ocean has been long sought. As discussed above, nutrient limitation is the primary throttle on marine productivity over much of this “ocean desert” and habitat is the key to increasing sediment size. The effect can be dramatic, while current sequestration flux to the benthos in the form of “marine snow” and fecal pellets may be on the order of 0.43 GtC/yr out of global marine productivity of 50 GtC/yr (with an open ocean component of 10 GtC/yr), less than 10% of pelagic sediment actually reaches the ocean floor. Sinking rates for coccoliths in pellet form are 160 m/day versus 0.15 m/day for the discrete coccoliths; and fecal pellets sink at rates up to 2000 m/day [Huneke H and R Henrich. 2011. Pelagic sedimentation in modern and ancient oceans. In, Deep-Sea Sediments. Huneke and Mulder (eds) Dev Sedimentology 63, page 222-231]. Thus, although current open ocean output as a sink for fixed carbon of 0.4 GtC/yr compares poorly to an annualized human carbon output equivalent to 6-7 GtC/yr, any endeavor that increased surface steady state sediment production from 0.001 gm/m2/day to 1 or 3 gm/m2/day (a 103-fold increase) in a form that sediments rapidly is expected to have a dramatic planetary cooling effect in a short period of time if deployed over sufficient surface area. Biological communities such as eelgrass and coral reefs having stable productivity of 1-3 gm/m2/day are readily identified. On the scale of industrial production, devices of the invention covering 150,000 km2 or 300,000 km2 (somewhere around the size of Wyoming) may be contemplated at a cost that is substantially less than the alternatives.
The compositions and methods of the present invention bring welcome synergy to convergent interests: global warming, marine productivity, and carbon sequestration. A combination of modalities—modification of global albedo and enhancements in marine productivity with associated increases in sedimentary lithification of atmospheric CO2—addresses the global climate crisis in multiple ways. There is a need for geoengineering that overcomes the dangers and difficulties discussed in the introductory remarks here, at a scale likely to have a significant impact on the global energy balance, while further providing some added economic benefit in the form of commodities or carbon credits so as to have a measurable incentive for implementation. Needed is a solution with a near-instantaneous effect that is readily measurable in direct physical terms, is rapidly deployable, and yet can be allowed to dissipate or vanish of a timescale of one or more years following implementation, without further intervention. In short, as will be shown here, reflective forced cooling of the planet is a plausible answer to the problem of global warming and can be fitted into a business model with appropriate incentives. Similarly, geoengineering of the atmosphere by marine sequestration of carbon dioxide at depth is also doable and can be incentivized for investment. Devices, methods and means for achieving these ends are aspects of the invention as laid open herein.